Attrition mill apparatus



March 23, 1965 c. D. FISHER ATTRITION MILL APPARATUS 4 Sheets-Sheet 1 Filed Oct. 5, 1962 March 23, 1965 c. D. FISHER ATTRITION MILL APPARATUS 4 Sheets-Sheet 2 Filed Oct 5, 1962 INVENTOR awe-J72? .w/wap F/Jl? March 23, 1965 c, FISHER 3,174,695

ATTRITION MILL APPARATUS Filed 001:. 5, 1962 4 Sheets-Sheet 5 INVENT (net/i? M/VAUD 4 March 23, 1965 c. D. FISHER 3, 7

ATTRITION MILL APPARATUS Filed Oct. 5, 1962 4 Sheets-Sheet 4 IN VEN TOR. (45:75:? 004413 inf/f5? United States Patent 0 3,174,695 ATTRITIGN MILL APPARATUS Chester Donald Fisher, Money, Pa, assignor to Sprout, Waldron Co., llnc., Muncy, Pa, a corporation of Pennsylvania Filed Oct. 5, 1962, Ser. No. 228,674 6 Claims. (Cl. 241-146) This invention relates to attrition mill apparatus and, more particularly, to rotating disc attrition mills for refining paper pulp and like uses and in which the attrition or refining or grinding action is obtained by passing the material to be treated between attrition surfaces formed on opposite faces of a rotating disc operating between cooperating non-rotating discs and, further, which apparatus may be of relatively small size and adapted for pressurized operation.

As will be understood, with rotating disc attrition mills of the character to which this invention relates (whether the attrition action be provided by a single disc rotating in cooperation with a mating stationary surface or by opposed and mating counter-rotating attrition disc surfaces), the severity or extent of attrition work done on ma- :terial being passed between the discs is an important function of, among other things, the maintained spacing between the mating or cooperating surfaces of the discs. Such passing of material between the discs, however, produces substantial moments of thrust force axially of the machine opposing whatever mechanism is provided for maintaining the discs axially spaced with the desired small clearance. The resistance of such substantial axial forces (which, as will be understood, increase tremendously as the diameter of the discs increases) may require expensive and complicated mechanism for the maintenance in operation of close tolerance spacing between the attrition surfaces as is desired and required for many uses of such attrition mills or refiners.

Similarly, if it is desired to incorporate such a disc attrition mill in a closed pressure fluid system so that the pressure is maintained within the attrition mill on, for example, a liquid slurry being treated thereby, difficulty may be experienced in providing adequate power into the mill and/ or a wastage of power may result from fluid friction and hydraulic losses. Any or all of the above factors may be disadvantageously increased, for any given amount of work to be performed on the material being treated as the size or diameter of the discs is increased, and certain important economies may be obtained by utilizing an attrition mill structure in which there is provided a rotating disc with effective attrition surfaces on both sides thereof and supported in cooperating and mating relation with two opposed and oppositely directed non-rotating discs to achieve, with the two opposite faces of the rotating disc, an effective working area comparable to that which could be obtained only with substantially larger diameter discs if there were but a single pair of cooperating working surfaces.

As will be understood, of course, the utilization of such an arrangement with a single rotating disc operating between two non-rotating attrition surfaces may provide for a general diminution of rotating disc surface area for the same amount of work to be performed, but the resulting economies in overall size and weight and expense of the apparatus are not necessarily linearly or directly proportional to the necessary disc diameter. For example, a particular application of such apparatus may permit a diameter reduction in the rotating disc of, perhaps, from 5 feet to 4 feet with substantial savings of power and of ease of operation, etc, but without necessarily permitting or requiring a basic change in the overall supporting and bearing and similar constructional elements of the entire apparatus. Thus, relatively minor (or, at least, not drastic) economies may be effected by decreasing the disc diameter from 5 feet to 4 feet, while still requiring a relatively complex and quite heavy and expensive machine which is both diflicult and expensive to manufacture despite tremendous savings and operating economy.

For particular applications where the advantages of such a general arrangement of double-sided attrition discs requires an effective diameter of no more than a foot or so, it may become no longer expedient merely to manufacture a miniature version of the larger machine and/or merely scaling down a larger machine may not produce the desired savings in either manufacture or operation in the absence of substantial and fundamental changes in the overall arrangement conceived particularly for accommodating the special or peculiar situations and factors involved in a commercial application for attrition mill apparatus of the character described with which satisfactory results may be achieved with such a drastically smaller size machine.

According to this invention, then, attrition mill apparatus of the character described is provided for obviating or minimizing the foregoing ditliculties and for producing maximum eihciency and economy of manufacture in use for applications or uses which may be satisfactorily accommodated by apparatus in which the effective diameter of the rotating and non-rotating attrition surfaces is in the range of about 1-3 feet or, at least, well below the range of 4 or 5 feet as conventional with various disc type attrition mills generally of the character to which this invention relates; and attrition mills embodying this invention include a rotating disc both opposite faces of which provide attrition surfaces for mating or cooperating attrition action with opposed non-rotating surfaces and in which the rotating disc is mounted on a freely axially floating shaft free to move axially under the inherent pressure forces acting on the opposite facesthereof as material to be treated is forced between the two pairs of opposed attrition surfaces; yet with all the cooperating and supporting and axially thrust-resisting portions of the apparatus particularly provided to withstand or accommodate the particular stresses and forces imposed upon such relatively small sized apparatus with specificeconomies in manufacture and operation thereof. As a further feature of this invention, arrangements or apparatus are provided whereby substantially the entire thrust forces encountered in such an attrition mill are withstood and accommodated substantially entirely by closely and directly coupled casing members of non-rotating or .stationary parts and substantially independently of the supporting base and bearing and drive members for the rotating portions of the apparatus; and including specific arrangements of the various portions of the apparatus which must be adjusted or removed in use so as to be no larger than can be readily handled manually when removed so as to be useful without extra cranes or hoists and/ or without extra built-in provisions merely for the handling and moving of heavy weights.

With the foregoing and additional objects in view, this invention will now be more particularly described, and other objects and advantages of this invention will be apparent from the following description, the accompany? ing drawings, and the appended claims.

In the drawing:

FIG. 1 is a top plan view of attrition mill apparatus embodying and for practicing this invention;

FIG. 2 is a side elevation of the apparatus of FIG. 1;

FIG. 3 is a vertical axial section through the apparatus of FIGS. 1 and 2 taken along the line 33 of FIG. 1;

FIG. 4 is an end elevation of the apparatus. ofFlG. 1;

FIG. 5 is a detailed elevation view on a somwhat larger scale and partly broken away of an arrangement for the axially adjustable non-rotating disc of the apparatus of FIG. 3 looking from the right hand end thereof;

FIG. 6 is a detailed elevation view on a somewhat larger scale of the rotating disc in the apparatus of FIG. -3 looking from the right hand end thereof;

,'FIG. 7 i's a detailed view of the hollow hub or rotor elementof the apparatus of FIG. 3 to which the rotating .dis cjs attajched; and

FIG. 8 is a partial detailed view on a somewhat larger scale of remote control hydraulic means for adjusting the axial spacing in one form of apparatus embodying and forpracticing this invention.

Referring to the drawings, in which like reference characters refer to like parts throughout the several views thereof, apparatus embodying and for practicing this inyention is illustrated as including a base or main frame 10 having two upright bearing supports 11 and 12 spaced apart on the left hand half ofbase 10 and a casing supportsection 13 on the right hand half of base 10 for supporting thereon a substantially cylindrical casing formed of two axially separable portions '15 and 16 meeting substantially along a transverse vertical plane through the apparatus. Preferably, upright bearing supports 11 and '12 are unified (in view of the construction described below) into an outer frame 'or casing as by a top 17-. As indicated more particularly in FIG. 3, a main shaft 20 is shown as mounted or journaled in antifriction bearing units indicated generally at 21 and 22, which are supported respectively in bearing supports '11 and 12 in such manner that bearing units 21 and 22 are free to slide axially in cylindrical supports 11 and 12, for the reasons and in the manner describedbelow in more detail. Main drive means for rotating shaft 20- are illustrated generally by V-belt pulleys 23 and a multiple V-belt drive 24 for transmitting power in known manner from a motor (not shown Alternative power transmission means are also indicated for connecting a direct drive to a motor as by having the left hand "end of shaft 20 protruding from the apparatus and, preferably, being provided with a safety cover 25 for enclosing the shaft end when the V-belt drive is being utilized. -Atthe opposite or right hand 'end of shaft 20 thereis provided a hollow hub including a sleeve portion 31 engaging over the right hand end of shaft 20 and affixed thereto as by welds indicated'at 32. Mounted on the righthand end of hollow hub 30 as by bolts 34 is rotatingdisc 35 carryingon opposite circular faces thereof attrition or grinding plates 36 and 37 as described in more detail hereafter. The hub portion 40 of rotating disc 35 is also hollow and forms with hollow hub 30 a cylindrical and open hollow rotor structure having a plurality radially directed passages (42in hollow hub 36 and hollow -hub 40) communicating between the inside of the hollow hubs or rotor and the outside thereof on each o ppo site side ofrotating disc 35. V

A transverse annular partition 45 is provided in cylinas'ingr's to form a non-rotating disc adjacent r0- tatlng disc '35, and includes mounted on the right hand face thereof non-rotating attrition or grinding plates 46. An 'axialsleeve portion 47 extending from annular partifish or disc '45 around the axial portion 31 of hub 30 onshaft 20, includes packing gland means indicated generallyat '48 in liquid sealing engagement around sleeve for providing in known and well understood manner a liquid sen "around that: '20 and sleeve 31 thereon duringbothrotating' "and axial movement thereof in packing gland 48. j As noted-above, in addition to cylindrical casing portion -1 5, there is also provided cylindrical casing portion 16, engaged with 15 as by 'a plurality of bolts indicated at 49 with both casing portions 15 and 16 being supported r as a unit 'onbase 10 as by webs or ribs 13 arnas'ernicylindrical configuration, and easing por- V is, in turn, affixed to upright '12 as by bolts 50.

W thin portion 16 of the casing (which forms a thrustresisting cover as noted below) there is provided an annular web or partition 55, forming another non-rotating disc adjacent rotating disc 35 and carrying on the left hand face thereof non-rotating attrition or grinding plates 56. Disc or partition is mounted for limited axially sliding movement within casing 16, sealing means 57 being preferably provided around the periphery of disc or partition 55 in liquid sealing engagement with the inner circumferential surface of easing 15-16 for providing, in known maner, a liquid seal during axial movement of disc 55. As indicated in the drawings, non-rotating disc 55 has a central circular opening of substantially the same diameter as the outer diameter of hollow hubs 30 and 40, and is provided with a conical central portion 58 and a central shaft or core member 59 engaging a sleeve 6!} affixed to the outer end cover 61 of casing member 16 whereby, as will be understood, disc 55 and plates 56 thereon may be displaced or adjusted axially within cylindrical casing 15 16 as core 59 slides axially in sleeve 60 of end cover 61.

As one illustrated embodiment of means for controlling or adjusting such axial positioning of non-rotating disc 55 may be noted the provision of a hand wheel having a hub portion 66 threadably engaging a threaded stud 67 engaged fixedly in core 59. Bearing structure indicated at 7'0 and mounted in end cover 61 of casing 16 permits free rotation of hand wheel 65 and hub 66 thereof while fixing both axially. In this manner, it will be understood, rotation of hand wheel 65 about non-rotating threaded stud 67 moves non-rotating disc 55 axially one way or the other depending upon the direction and extent of rotation of hand wheel 65, thereby adjusting or determining the axial spacing between non-rotating disc 45 and non-rotating disc 55. i

A material inlet 75, for admitting material to be treated in the apparatus in the form of a liquid slurry or otherwise, is engaged through conical portion 58 on non-rotating disc 55 and extends upwardly through a slot '76 at the top of casing portion 16. Inlet 75, thus, communicates from the outside of the apparatus into the annular space within conical portion 58 and thus directly into the central hollow of hubs 3t and 40. Inlet 7 5 also moves axially with non-rotating disc 55. Because of the axial movement of inlet a flexible conduit or joint is utili'zed between the upper end of inlet 75 and whatever permanent piping or conduits are installed to conduct material to be treated to the apparatus, which flexible conduit is indicated generally as a hose 78 in FIG. 2 with conventional and appertaining coupling means 79 for engaging the end of inlet 75.

As will be apparent from the foregoing, a slurry or other material to be treated in the attrition rnill apparatus is introduced through inlet 75 and flows thence into the hollow center portion of the rotor formed by hubs 30 and 40. As shaft 20 rotates, along with rotor 36-40 and rotating disc 35 mounted thereon, material introduced through inlet 75 is forced outwardly by centrifugal force through radial passages 42 and 43 in the rotor and, thence radially outwardly on each opposite side of rotating disc 35 and for grinding and attrition action between the respective operating or mating grinding plates 36, 46 and 37, 56 to be discharged into the annular discharge passage within cylindrical cover '15 and radially outwardly of rotating disc 35 and both sets of attrition plates 36, 46, and 37, 56 after having been subjected to the desired grinding or attrition or other work during passage between one or the other of the two sets of attrition plates. As indicated more particularly in FIGS. 1 and 4, cylindrical casing 15 is preferably provided with a plurality of outlet openings and various angular positions therearound for discharging material from the apparatus after passage between the sets of attrition plates, and with such discharge openings being disposed at whatever angular positioning may be desired with regard to whatever piping or installations are to follow the apparatus as installed. For example, horizontally diametrically opposite outlet openings are shown in FIGS. 1 and 4 with a material dis-.

charge outlet or pipe 80 being illustrated in left hand opening of FIG. 4, while a plug 81 is shown closing the other alternative or optional opening in Fig. 4.

As indicated in more detail in, for example FIG. 6, attrition plates 37 are preferably formed in a plurality of segments and bolted onto each opposite face of disc 35 as by bolts 85. The attrition surfaces of plates 37 (indicated only diagrammatically by the surface lines in FIG. 6 may satisfactorily be a wide variety of grinding surfaces all well known and understood in this art. Attrition plates 37 are to be affixed to one face of rotating disc 35 (the right hand face visible in the view of FIG. 6), while attrition plates 36 are to be similarly affixed to the opposite face of disc 35. A preferred arrangement therefore is to provide in disc 35 a plurality of tapped holes 86 for plates 37 on one side of disc 35 and a similar plurality of tapped holes 87 threaded from the opposite side of disc 35 for accommodating bolts such as 85 for afiixing plates 36 to the opposite side. The series of holes 86 is stag gered with respect to the series of holes 85 as indicated in FIG. 6.

A similar set of tapped holes 88 are provided in nonrotating disc 55 for accommodating bolts 89 for afiixing a similar set of cooperating attrition plate segments 56 to disc 55 (as indicated in FIG. as a View of disc 55 looking from the right hand end of the apparatus), and plates 46 are similarly fastened to non-rotating disc 45. FIG. 5 also illustrates the radial reinforcing webs 91) on the back of disc 55 for supporting the disc for axial sliding movement within casing 16 on guides 91 around the inside of casing 16.

As further indicated in detail in FIG. 7, a preferred structure for hollow hub is shown in elevation as including equally spaced therearound tapped borings 95 for receiving bolts 34. A plurality of holes 96 are also formed in the annular surface of hub 30 for accommodating butt welds 32 to the right hand end of shaft 20 for fixing hub 36 and the axially extending sleeve 31 thereof to the main shaft.

As will be understood, the control of the work being done by the pairs of opposed attrition surfaces or plates is normally achieved in disc attrition mills by adjusting the close spacing therebetween-i.e., the axial spacing between rotating disc and each of the non-rotating discs and -with accurate and precise control of such close spacing being maintained within close tolerance limits frequently measured in terms of thousandths of an inch. In constructions embodying this invention, such spacing and the control and maintenance thereof is achieved by a combination of the axial displacement or adjustment of the positioning of non-rotating disc 55 and the axially floating arrangement of shaft 20 and rotating disc 35 thereon.

Thus, with rotating disc 35 axially freely floating, the axially positioning of disc 35 will be determined between non-rotating discs 45 and 55 as influenced by the hydraulic pressure forces on either side of disc 35 arising from the material being treated. By the same token, adjustment of non-rotating disc 55 to any particular axial positioning automatically causes axial adjustment of rotating disc 35 as material to be treated is fed on either side thereof. For this reason, it is preferred that the several radial passages 42 and 43 in the hollow rotor formed by hubs 30 and 41} be arranged with substantially equivalent throughout capacities for introducing substantially equal quantities and flow of material on both sides of disc 35.

Similarly, as noted above, it is preferred that main shaft 20 and disc 35 thereon be freely floating axially for at least a limited extent. Such free axial floating arrangement is obtained in the illustrated embodiment as by having bearing units 22 axially slidable in the respective bearing supports 11 and 12. Thus, each bearing unit 21 and 22 includes a cylindrical outer housing 1% within which are enclosed antifriction bearing means indicated at 101 for rotatably supporting main shaft 20 and which need not contain any thrust-resistant bearing means. That is, although bearing units 21 and 22 may be axially fixed with respect to shaft 20, no axial thrust forces along shaft 20 need be resisted by the bearing 101 because each of the bearing units 21 and 22 is supported in cylindrical journals 102 and 103, respectively, in bearing supports 11 and 12 for free axial sliding movement therein. Indeed, it may be preferred to provide lubricat ing means (as indicated generally by the grease nipple 1114) to assure completely free sliding movement of hearing units 21 and 22 in the cylindrical bearing supports.

Thus, as rotating disc 35 is urged axially one way or the other by the pressure forces to which it is subjected, main shaft 20 and the bearing units 21 and 22 thereon are free to execute similar axial movements in cylindrical journals 102 and 103 of bearing supports 11 and 12. In this manner, not only is rotating disc 35 readily and accurately positioned with respect to both of the non-rotating discs 45 and 55 as adjusted by the axial adjustment of disc 55, but the entire necessity for thrust-resisting components or mechanism effective on main shaft 20 is eliminated from the construction with consequent and substantial savings in manufacturing economies and massiveness of the resulting apparatus.

As will be understood, of course, such extent of axial movement of main shaft 20 need not be particularly great, satisfactory results having been achieved with apparatus embodying this invention with a maximum extent of axial floating movement for shaft 20 of less than an inch. With the V-belt drive illustrated, such axial movement of shaft 20 is readily accommodated, although it is preferred to have rather wide spacing between the center line of driven pulley 23 on shaft 26 and the center line of a drive pulley on the motor so that V-belts 24 are of a length substantial enough to avoid resistance to such axial movement of shaft 20 by the inherently self-centering nature of a V-belt drive. With a direct drive of the motor coupled to the left hand end of shaft 20, alternatively conventional means are readily available for a drive coupling permitting limited free axial movement of shaft 20 with respect to a motor coupled to the end thereof.

As noted above, such axial adjustment or positioning of non-rotating disc 55 is accomplished in the embodiment illustrated in FIG. 3 by means of hand wheel 65 operating on threaded stud 67 in core 59 of disc 55. An additional or alternative adjustment means for the axial positioning of disc 55 is illustrated in FIG. 8 as particularly adapted for remote control, and as utilizing a hydraulic or pneumatic cylinder-and-piston arrangement for moving disc 55 in either direction axially and/or maintaining it in position as desired.

Thus, referring to FIG. 8, an enlarged detail of the right hand end of end cover 61 is shown, including sleeve 60 in which is slidably carried core 59 on a conical central portion 58 of non-rotating disc 55. Instead of the rotatable hand wheel and bearing and threaded stud arrangement of FIG. 3, however, a cylinder mounting plate is mounted on the right hand or outer side of cover 61 as by bolts 111, and an hydraulic or pneumatic cylinder arrangement is rigidly aiiixed to plate 110 as by tie rods 116. Cylinder 115 includes, in completely known and conventional manner, an axially reciprocal double acting piston indicated at 117 having piston rods 118 and 119 extending axially in opposite directions from piston 117 and slidably through packing or bushings 120 and 121 sealing the opposite ends of cylinder 115. Con ventional inlet-outlet lines or conduits 123, 124 are in dicated for admitting and discharging pressure fluid into cylinder 115 selectively on either side of piston 117 therein for controlling and adjusting the axial positioning and movement of piston 117 in cylinder 115.

On the left hand end of piston rod 118 is affixed a threaded stud 126 threadably engaged in a boring 127 in Sliding core 59, with, preferably, a set screw 128 for maintaining the fixed engagement and relation thereof. The right hand end of piston rod 119 carries a threaded stud 130, on which is threadably engaged a hand wheel 131 or other adjusting and operating device. On the right hand end of cylinder 115, and affixed thereto as by tie rods 116, is a hand wheel mounting plate 132 having an axial sleeve or collar 133 around piston shaft 119 and carrying bearing arrangement between plate 132 and hub portion 136 of hand wheel 131.

' As will be apparent from the foregoing, remote control of pressure fluidinto or out of cylinder 115 selectively through either line 123 or 124 moves piston 117 axially in cylinder 115, and, accordingly, imparts similar axial movement to non rotating disc 55 through core 59 'of conical portion 58 thereof. Similarly, setting hand wheel 31 at a given axial positioning along threaded stud 130 has the effect of limiting the extent of movement of piston 117 to the left in cylinder 115 as hub 136 on hand wheel 131 engages mounting plate 132 through bearing arrangement 135-'e.g., in substantially the position shown in FIG; 8. Thus, the ultimate axial spacing desired between non-rotating discs 45 and 55 can be pre- "set by the axial positioning of hand wheel 131 on threaded stud 130, and then disc 55 moved further into open position and returned to the pre-set position by remote control of cylinder-and-piston arrangement 115, 117, etc. When the piston 117 is moved to the right, the gap between the non-rotating discs 45 and 55 is increased as completely as possible or desired, yet when cylinder 117 is again moved to the left by pressure fluid in cylinder 1115, the closeness of the axial spacing of discs 45 and 55 is limited or controlled by pre-set hand wheel 131 engaging mounting plate 132 at the end of cylinder 115.

As a further convenience in the illustrated construe 'tion, an annular calibrated scale member 140 is shown rotatably mounted around hub 136 on hand wheel 131, with a cooperating pointer indicator 141 being mounted "on plate 132 or some other stationary part of the appa- "ratus in readily visible position. A set screw 142 is provided through hand wheel 131 and engaging annular scale member 140 in such manner that scale member 140 may be rotated with respect to hand wheel 131 and pointer 141 to establish calibrated axial positions of disc 55 in terms of the angular position of hand wheel 131. Thus, hand wheel 131 and the axial positioning thereof on threaded stud 130 is readily visually pre-set for a given desired limited spacing of discs 45 and 55. Also, in the construction illustrated, an annular row of axial serra- 'tions or teeth (indicated at 145) is preferably provided 1 around hand wheel 131 for cooperating engagement with a fixed pawl 146 for releasably locking hand wheel 131 in any particular angular positioning on threaded stud 130 to maintain the desired axial positioning of hand wheel 131 to limit the closing or leftward movement of piston 1 17 and non-rotating disc 55. a

As a further feature of the illustrated embodiment of this invention and the particular construction thereof may be noted the fact that bearing supports 11 and 12, cylindrical journals 102 and 103 thereon, housing 17 at the top thereof, and the supporting structure 13 for cylindrical casing members 15 and 16 are all integrally formed with base 1 as a single unified structure in any convenient manner. Furthermore, all the load-carrying surfaces of the aforementioned structures are of circular cross-section and co-axial disposition so that all the sur faces thereof which engage or carry or support bearings 'or other rotating or axially moving portions of the appa- "ratus (e'.g., the inner surfaces of cylindrical bearing supports 102 and 103 and the supporting surfaces of webs '13) are readily machined and finished by a simple rotary machining operation on the same co-axial centers to provide and maintain absolute co-axial alignment of the various cylindrical supporting surfaces, and, hence, all

the various -co-axial moving parts of the device. Similarly, the enclosing contact between main shaft and sleeve 47 in casing 15 is also of circular cross-section and includes cylindrical packing gland 48 in a manner to maintain (or, at least, not to disrupt) the desired axial alignment of the various moving or rotating parts in the assembling or in the operation of the apparatus.

By forming casing 15, 16 as cylindrical elements and by mounting or supporting axially moving non-rotating disc 55 wholly in one of those elements along with the means for axial adjustment thereof, the task of opening the machine for access to the Various discs in order to change attrition plates thereon or otherwise is substantially simplified. Thus, all that is necessary is to loosen the several bolts 49 and slide casing portion 16 (including axially adjustable disc 55 and all the appertaining structure thereof) along supporting Webs 13 of base 10. In a relatively small attrition mill device (e.g., with a disc diameter of about 12 inches more or less), casing 16, including thrust cover 61 and disc 55 and associated parts, may be made small and light enough to be readily handled without even the necessity for overhead hoists, etc.

Removal of casing 16, of course, gives access to at trition plates 56 on disc 55 and, similarly, access to plates 37 on the right hand face of rotating disc 35. Merely removing bolts 34, then, permits the ready removal of rotating disc 35, thereby giving access to plates 36 on the left hand face thereof and to plates 46 on nonrotating disc 45. Accordingly, all the plates can be exposed and changed, the device reassembled in a relatively short time, and with very little labor or effort. Also, since the inlet piping to inlet 75 is flexible '(and/ or coupled with a quick change coupling such as 79), such inlet piping does not interfere with the aforementioned operations. Since the discharge or outlet 80 is positioned in portion 15 of the cylindrical casing, instead of in removable portion 16, it is in no event necessary even to disconnect the outlet piping from the machine for a plate change or other access into the interior of the grinding or attrition portion of the apparatus.

As a further additional feature of this invention, all bearings for main shaft 20 are directly supported on base 10 (through bearing supports 11 and 12) and cylindrical casing members 15, 16 are also directly supported on base 10 but separately from the shaft bearing support structures. Thus, the entire thrust path to be resisted by the device, as material to be ground is forced between the opposed pairs of Working surfaces of Totating disc and non-rotating discs and 55, is contained wholly within cylindrical casing 15-16, rather than depending upon the rigidity of the entire base or main frame to resist axial thrust forces. That is, the possible axial thrust forces to be resisted are those tending to urge non-rotating discs 45 and axially apart as material is forcedtherebetween to have attrition work performed thereon. As will be noted, particularly, from FIG. 3, such thrust forces are directly resisted by the adjusting mechanism for disc 55, carried wholly by the end thrust cover 61 of cylindrical casing 16. This cylindrical casing portion is, in turn, directly and co-axially engaged with cylindrical casing 15, carrying disc 45, 'around the meeting edges thereof by bolts 49. The result of such arrangement is that main base 10, bearing supports 11 and 12, and casing'supports 13 are substantially free of axial thrust forces and may, therefore, be manufactured of somewhat lighter Weight construction than would be the case if such thrust forces were trans- 'mitted through the entire length of the base or were resisted by thrust bearings or other mechanisms directly effective on shaft 20.

Because of the freely floating nature of disc 35 and 'main shaft 20, of course, such forces occurring in operation are not transmitted thereto, but are substantially entirely transmitted through and resisted by cylindrical casing portions 15, 16 and thrust cover 61 thereof in close coupled fashion and independently of both the base supporting structure and the mechanism provided for free axial movement of main shaft 20. More importantly, such thrust forces are insulated from imparting to the supporting structure moments of force which tend to cause misalignments of the various supporting or rotating parts during operation. Since the thrust forces are all locked between stationary (or, at least, non-rotating) parts, flexures or other misalignments of the necessarily coaxially rotating structures are avoided with a substantially less heavy construction of base 10, which, in accordance herewith, merely has to support the weight of the various moving parts, without resisting thrust-engendered misalignments thereof. Also, since non-rotating discs 45 and 55 are uniformly supported all around the circumferences thereof in uniform manner from or by outer cylindrical casings 15, 16, thrust transmission is uniform around the circumferences thereof so there is no tendency for transverse deflection of the non-rotating discs more in one sector than in another thereof, with resultant ease in maintaining absolute parallelism therebetween to avoid non-uniform deflections which might cause actual contact between the moving attrition plates in very close axial spacing thereof, and yet with a relatively light form of construction.

By so reducing the length of thrust path for resisting axial thrust forces, there is substantially entirely eliminated the situation where axial thrust forces are transmitted through a large number of separate supporting structures, minor flexing of any one or all of which has a cumulative effect upon deflections or misalignments. For example, even with relatively light support design, the apparatus is satisfactorily operated with axial clearances of as little as of an inch between the cooperating attrition faces of plates 36. 46 and 37, 56 without deflection or spring of the surfaces sufficient to cause clashing or actual contact of the moving surfaces even with some non-uniformity or interruption of flow of material into inlet 75. As will be understood, of course, a conventional pressure or flow sensing switch or device is readily inserted, if desired, to make a signal or stop the machine or back off disc 55 to the right automatically upon a drop in inlet pressure as might occur with failure of stock flow. On the other hand, and direct and short coupled thrust-resisting elements adequately accommodate surges in stock flow, also Without momentary flexing or deflection to an unsatisfactory or intolerable extent, even at such close clearance operation.

Accordingly, as will be apparent from the foregoing, there is provided in accordance with this invention rotating attrition mill apparatus of the character described and readily adapted for pressurized operation, yet particularly arranged for smaller sizes of such apparatus as may be desired for certain particular applications. Not only does this apparatus provide the advantages resulting from a freely floating rotating disc and shaft, as well recognized and desirable with larger machines, but it also is specifically arranged to accommodate the particu'lar versatility of operations and thrust forces encountered in such applications for smaller machines by particular arrangements of construction and parts provided especially therefor and for problems peculiarly as sociated therewith, rather than being merely a scaled down miniature of larger machines, in this manner to include enhanced manufacturing economies and enhanced case and economies of operation for a wide variety of particular attrition or grinding applications.

While the forms of apparatus herein described constitute a preferred embodiment of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a disc type rotating attrition mill apparatus havlfi ing a base, a generally horizontal shaft and a rotor mounted thereon for cooperating attrition work with respect to both of two opposed non-rotating attrition discs between which said rotor rotates, the combination which comprises a cylindrical casing supported on said base, said casing being formed of two disengageable parts joining on substantially a vertical transverse plane and enclosing said rotor and non-rotating discs, means for axially retracting one of said casing parts for access to said rotor and non-rotating discs, a horizontal shaft for said rotor, a transversely arcuate support surface on said base parallel to and concentric with the rotational axis of said shaft for receiving said casing, said support surface be-ing complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with the shaft and rotor, axially slida-ble bearing means for mounting said shaft in said apparatus for rotation of said rotor between said opposed non-rotating discs and disposed entirely outside of and on one side of said casing, drive means for rotating said rotor through said shaft, and means for axially displacing and adjusting the axial positioning of at least one of said nonrotating discs with respect to the other and with respect to said rotor, and said axially adjustable non-rotating disc and said axial displacing and adjusting means therefor being disposed in said retractable part of said casing.

2. In disc-type rotating attrition mill apparatus having a generally horizontal axis and a rotor mounted thereon for cooperating attrition work with respect to both of two opposed non-rotating attrition discs between which said rotor rotates, the combination which comprises a base for supporting said apparatus, a horizontal shaft for said rotor, bearing means for mounting said shaft for rotation of said rotor between said opposed non-rotating discs and disposed entirely to one side of both said non-rotating discs, said bear-ing means including means for free axial floating displacement of said shaft and said rotor with respect to said non-rotating discs, means for supporting said bear-ing means directly on said base, a cylindrical casing enclosing said rotor and non-rotating discs, means for supporting said casing on said base entirely to one side of said bearing means for said shaft, said means for supporting said casing comprising a transversely arcuate support surface on said base parallel to and concentric with the rotational axis of said shaft, said support surface being complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with said shaft and rotor, drive means for rotating said rotor through said shaft, means for axially displacing and adjusting the axial positioning of one of said non-rotating discs with respect to the other and with respect to said rotor, said axial displacing and adjusting means being mounted in said casing for axial movement substantially independently of said axial movement of said floating rotor and said shaft, and said means for supporting said casing on said base and said bearing means on said base being integrally and coaxially formed therewith.

3. Attrition mill apparatus comprising a base, axially aligned bearing supports on said base, a shaft extending coaxially of said bearing supports, bearings rotationally mounting said shaft in said bearing supports, a rotor on one end of said shaft having attrition surfaces on 0pposed inner and outer radial faces thereof, a substantially cylindrical casing secured to said base enclosing said rotor, a transversely arcuate support surface on said base parallel to and concentric with the rotational axis of said shaft for receiving said casing, said support surface being complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with said shaft and rotor, said casing being formed of two axially separable portions comprising an inner casing portion radially overlying said rotor and a portion of said shaft and an outer casing portion remote from said shaft, said casing portions being joined along a substantial'ly vertical transverse plane,-a first non-rotating attrition disc fixedly secured transversely within said inner casing port-ion for cooperative attrition work with respect to the inner attrition surface of said rotor, a second non-rotating attrition disc transversely mounted on said outer casing portion for cooperative attrition work with respect to the outer attrition surface of said rot r, and means on said outer casing portion for adjusting the axial position of said second non-rotating disc.

4; Attrition mill apparatus comprising a base, axially aligned bearing supports on said base, a shaft extending coaxially of said bearing supports, bearing means for rotationally mounting said shaft in said bearing supports, 'a rotor on oneend of said shaft at one side of said bearing means and having attrition surfaces on opposed inner and outer radial faces thereof, said bearing means including means providing free axial floating displacement of said shaft and said rotor, a substantially cylindrical casing secured to said base enclosing said rotor at said one side of said bearing means, a transversely arcuate sup- "port surface on said base parallel to and concentric with the rotational axis of said shaft for receiving said casing, said support surface being complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with said shaft and rotor, said casing being formed of two axially separable portions comprising an inner casing portion radially overlying said rotor and a portion of said shaft and an outer casing portion remote from said shaft, said casing portions being joined along a substantially vertical transverse plane,

"a first non-rotating attrition disc fixedly secured transvcrsely within said inner casing portion for cooperative attrition work with respect to the inner attrition surface of said rotor, a second non-rotating attrition disc transversely mounted on said outer casing portion for cooperative attrition Work with respect to the outer attrieoaxially of said bearing supports, bearings rotationally mounting said shaft in said bearing supports, a rotor on one end of said shaft having attrition surfaces on opposed inner and outer radial faces thereof, a substantially cylindrical casing secured to said base enclosing said rotor,

a transversely arcuate support surface on said base parallelto and concentric with the rotational axis of said shaft for receiving said casing, said support surface being complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with said shaft and rotor, said casing being formed of two axially separable portions comprising an inner casing portion radially overlying said rotor and a portion of said shaft and an outer casing portion remote from said shaft, said casing portions being joined along a substantially vertical transverse plane, a first non-rotating attrition disc fixedly secured transversely within said inner casing portion for cooperative attrition work with respect to the inner attrition surface of said rotor, a second non-rotating attrition disc transversely mounted on said outer casing portionfor cooperative attrition work with respect to the outer attrition surface of said rotor, means on said outer casing portion for adjusting the axial position of said second non-rotating disc and for maintaining the alignment of said second non-rotating disc, said latter means comprising an end cover closing the outer end of tion of said second non-rotating attrition disc.

6. Attrition mill apparatus comprising a base, axially aligned bearing supports on said base, a shaft extending coaxially of said bearing supports, bearing means for rotationally mounting said shaft in said bearing supports, a rotor on one end of said shaft having attrition surfaces on opposed inner and outer radial faces thereof, said bearing means including means providing free axial floating displacement of said shaft and said rotor, a substantially cylindrical casing secured to said base enclosing said rotor, said casing and rotor being disposed to one side of said bearing means, a transversely arcuate support surface on said base parallel to and concentric with the rotational axis of said shaft for receiving said casing,

said support surface being complementary to the cylindrical outer surface of said casing to provide concentric alignment of said casing with said shaft and rotor, said casing being formed of two axially separable portions comprising an inner casing portion radially overlying said rotor and a portion of said shaft and an outer casing porof said rotor, and means on said outer casing portion for adjusting the axial position of said second non-rotating dlsc, and for maintaining the alignment of said second non-rotating disc, said latter means comprising an end cover closing the outer end of said outer casing portion and having a hollow sleeve secured coaxially with said shaft, a central shaft extending outwardly from said second non-rotating attrition disc engaged within said sleeve in axially slidable relation therewith, and means on said end cover for adjusting the axial position of said second non-rotating attrition disc.

References Cited by the Examiner UNITED STATES PATENTS 8/85 Cadwgan 241--146 9/51 Marco 241l46 J. SPENCER OVERHOLSER, Primary Examiner. 

1. IN A DISC TYPE ROTATING ATTRITION MILL APPARATUS HAVING A BASE, A GENERALLY HORIZONTAL SHAFT AND A ROTOR MOUNTED THEREON FOR COOPERATING ATTRITION WORK WITH RESPECT TO BOTH OF TWO OPPOSED NON-ROTATING ATTRITION DISCS BETWEEN WHICH SAID ROTOR ROTATES, THE COMBINATION WHICH COMPRISES A CYLINDRICAL CASING SUPPORTED ON SAID BASE, SAID CASING BEING FORMED OF TWO DISENGAGEABLE PARTS JOINING ON SUBSTANTIALLY A VERTICAL TRANSVERSE PLANE AND ENCLOSING SAID ROTOR AND NON-ROTATING DISCS, MEANS FOR AXIALLY RECTRACTING ONE OF SAID CASING PARTS FOR ACCESS TO SAID ROTOR AND NON-ROTATING DISCS, A HORIZONTAL SHAFT FOR SAID ROTOR, A TRANSVERSELY ARCUATE SUPPORT SURFACE ON SAID BASE PARALLEL TO AND CONCENTRIC WITH THE ROTATIONAL AXIS OF SAID SHAFT FOR RECEIVING SAID CASING, SAID SUPPORT SURFACE BEING COMPLEMENTARY TO THE CYLINDRICAL OUTER SURFACE OF SAID CASING TO PROVIDE CONCENTRIC ALIGNMENT OF SAID CASING WITH THE SHAFT AND ROTOR, AXIALLY SLIDABLE BEARING MEANS FOR MOUNTING SAID SHAFT IN SAID APPARATUS FOR ROTATION OF SAID ROTOR BETWEEN SAID OPPOSED NON-ROTATING DISCS AND DISPOSED ENTIRELY OUTSIDE OF AND ON ONE SIDE OF SAID CASING, DRIVE MEANS FOR ROTATING SAID ROTOR THROUGH SAID SHAFT, AND MEANS FOR AXIALLY DISPLACING AND ADJUSTING THE AXIAL POSITIONING OF AT LEAST ONE OF SAID NONROTATING DISCS WITH RESPECT TO THE OTHER END WITH RESPECT TO SAID ROTOR, AND SAID AXIALLY ADJUSTABLE NON-ROTATING DISC AND SAID AXIAL DISPLACING AND ADJUSTING MEANS THEREFOR BEING DISPOSED IN SAID RETRACTABLE PART OF SAID CASING. 